Amino acids proteins and DNA

• What is the general structure of an α amino acid?

  NH2, CH, CO2H, R
• What is the simplest amino acid?

  Glycine
• Why are all amino acids except glycine chiral?

  They have four different groups around C
• What do amino acids do to plane polarized light?

  They rotate it
• What classifies an amino acid as acidic or basic?

  Extra carboxylic acid or amine group
• What is the IUPAC name for aspartic acid?

  2-aminobutanedioic acid
• What is the IUPAC name for glycine?

  (2-)aminoethanoic acid
• What is the IUPAC name for lysine?

  2,6-diaminohexanoic acid
• What form do amino acids exist in?

  As dipolar zwitterions
• Why do amino acids have high melting points?

  Due to ionic interactions between zwitterions
• What are the acidic and basic groups in amino acids?

  Amine group is basic, carboxylic acid is acidic
• How do amino acids act as buffers?

  They resist pH changes with small acid/alkali
• What happens to the extra groups on the R group in different pH conditions?

  They react and change form
• What does the alpha in ‘α’ amino acid signify?

  Both NH2 and COOH are on the same C
• What are dipeptides?

  Combination of two amino acids with one amide link
• What is the general structure of an α amino acid?

  NH2, CH, CO2H, R
• What is the simplest amino acid?

  Glycine
• How many combinations can two different amino acids form in a dipeptide?

  Two possible combinations
• What reactions can the carboxylic acid and amine groups in amino acids undergo?

  Usual reactions of these functional groups
• Why are all amino acids except glycine chiral?

  They have four different groups around C
• What happens when proteins are heated with hydrochloric acid?

  They can be hydrolyzed into amino acids
• How can the composition of a protein molecule be deduced?

  Using TLC chromatography
• What do amino acids do to plane polarized light?

  They rotate it
• What classifies an amino acid as acidic or basic?

  Extra carboxylic acid or amine group
• What is the method for thin-layer chromatography of amino acids?

  1. Draw a pencil line on TLC plate.
  2. Add drops of each sample.
  3. Place in solvent chamber.
  4. Remove when solvent reaches 1 cm from top.
  5. Spray with ninhydrin and heat.
  6. Calculate Rf values.
• What is the IUPAC name for aspartic acid?

  2-aminobutanedioic acid
• What is the Rf value formula?

  Rf = distance moved by amino acid / distance moved by solvent
• What is the IUPAC name for glycine?

  (2-)aminoethanoic acid
• Why is ninhydrin used in chromatography of amino acids?

  To visualize transparent amino acids
• What is the IUPAC name for lysine?

  2,6-diaminohexanoic acid
• What happens when ninhydrin is sprayed on amino acids?

  Red to blue spots appear upon heating
• What form do amino acids exist in?

  As dipolar zwitterions
• Why should gloves be worn during chromatography?

  To prevent contamination from hands
• Why do amino acids have high melting points?

  Due to ionic interactions of zwitterions
• What is the primary structure of proteins?

  Sequence of 20 different amino acids
• What is the acidity and basicity of amino acids?

  Amine group is basic, carboxylic acid is acidic
• What is the secondary structure of proteins?

  Folding into α-helices or β-pleated sheets
• What happens when amino acids are added to acid or alkali?

  They act as weak buffers
• How are secondary structures held together?

  By hydrogen bonds between amino acids
• What happens to the extra groups on the R group in different pH conditions?

  They react and change form